The present invention relates to a novel process for preparing L-methionine from DL- or L-N-carbamoylmethionine by employing cells or treated cells of microorganisms.
In general, optically active L-amino acids are directly prepared by fermentation or prepared by optically resolving chemically synthesized DL-amino acids. No advantageous method for directly preparing L-methionine by fermentation is known, and L-methionine is prepared exclusively by subjecting chemically synthesized DL-methionine to N-acetylation and selectively hydrolyzing only L-N-acetylmethionine by employing acylase enzyme. However, such a method has the disadvantage that the cost becomes dear, since the acetylation of DL-methionine must be conducted and moreover expensive acylase must be employed. The thus prepared L-methionine is expensive and, therefore, the use thereof has been limited to medicines.